Thoughts on this amp

I'm stuck at home, bored, with germs and have been using some of the time to try and get a dedicated 2 channel system back together via some slightly random online s/hand purchases, having recently sold a few bits off in preparation for a now abandoned house move. Anyway, I have just bought a power amp and am awaiting its delivery in a few days, and whilst I am waiting, I wondered what others thought of how it is put together?

I wont disclose the make/model at present (and if you know maybe you can hold off posting the name for a day or so to allow unprejudiced opinions), I just wonder what others think of its construction/design/component quality? Ignore the 120v tap on the transformer, I'm in the UK and the picture is just one I found on line. Cost was about £120.00/US$190.00, and assuming all working okay, what do others think of its relative value if bought new today? Be as kind or harsh as you like within reason, I already feel ropey and don't think a few comments will make me feel any better or worse . Here it is:

 

Undersized transformer... not great with speakers below 90db efficiency. But pleasing with efficient speakers in a small (UK standard) sized room. Considered this but went integrated with Arcam delta90 at the time.

 

Really? That's interesting, thank you. My speakers and room certainly check both those requirements (90dB/not really dipping below 8 ohm speakers in a room roughly 13.5' x 13'), though I thought the transformer looked a reasonable size. I've certainly had power amps that have worked very well which definitely had smaller transformers, possibly helped by the fact I don't often listen at particularly high volumes. I have been looking at Arcam amps but haven't found a power amp within budget, or at least not one in the cold-befuddled 2 days that I have been looking in ernest. I will keep an eye for the future in case the amp en route to me doesn't work as hoped.

 

FWIW, here are my thoughts. It is obviously dual mono design with a shared power supply. I hope the big blue caps are not electrolytics and that is a boat load of transistors all attached to the same heat sink. Since I have no idea how much power this amp is suppose to deliver it is hard to say if you will have a thermal problem with it. I do not see a built in cooling fan anywhere so if this amp is suppose to deliver something like 200 watts per channel I would be careful about it getting to hot.

 

Looks like it should fit your situation well

 

My first thought was this is a British unit that is widely cloned with repro boards widely available on ebay UK (but never ebay US even though the same vendors sell stuff like Marantz 7/Mc C22 clone boards) but it isn't.

It doesn't stand out as either particularly cheesy nor particularly impressive. It's clearly nowhere mil spec. But neatly built for a consumer piece.

Two things stand out, it has a toroidal PT, which is okay, so long as the AC has no DC component to it ( a DC offset). If it does it will saturate, get hot, and perform poorly or perhaps overheat. Also, the circuit board material is that blue dull thermoset stuff popular in the late 70s and through much of the 80s. It was actually a premium price material but the adhesive that bonds the copper to the plastic ages poorly and when any but the most skilled equipped with thermally controlled irons tries soldering on it the pad comes up. Sometimes does anyway. So if repairs are needed plan on kluge wires and superglue.

 

Interesting comments, thanks. The amp is roughly 70 watts per channel with the case itself also acting as a heatsink (there's a reference in the service manual I found specifying the need to ensure the case bolts are tight so as to ensure heatsinking works correctly). Big blue caps are 10000uF electrolytics: don't a lot (most?) of amps use electrolytics in the power supplies? Easily available for servicing, as and when required, which is one of the reasons (along with a full service manual available online) it appealed. Era wise, the suggestion of 80s is right, designed in about '85, I think, though mine is from a production from about '89.

 

The best amps use no electrolytics, even in the power supply. The problem with electrolytics is hysteresis (http://en.wikipedia.org/wiki/Hysteresis) which is not desirable anywhere in the amp.

The hysteresis is caused by Dielectric Absorption which is high in electrolytic capacitors ( http://en.wikipedia.org/wiki/Dielectric_absorption#Measurement).

 

Yes indeed ! And those look the size of friggin' soda cans ! Nice toroidal and 8 PT per channel. I like it. Tell us the brand when you see fit to please.

 

i've never owned an amp with a fan...

 

I place powerful 220volts aluminium fans on top of both my amps to suck out the hot air. This prolongs their lifespans.

 

ok, i've never done that or had any problems with heat...amps get hot, they are designed for this...

 

I've blown many a one, so I'll stick with my fans. I remember my first amp, a Kenwood KA-300 (25wpc). I drove it so hard you could not touch its top without burning your hand. I think I could have fried an egg there. Only thing that prevented me from driving it harder sometimes was distortion. It never failed though. Tough, good-sounding little MF

 

hey, whatever works, works...

ha...

another thing someone said something about transformer noise because of DC , i use a "humdinger" on mine and it took it away...

http://avahifi.com/index.php?option=com_content&view=article&id=270&Itemid=239

 

Looks good on paper. Anyone ever tried one ?

 

Well, interesting conversation.

 

For those wanting to know, the amp in question is a Heybrook P2 power amplifier. Designed by Tim de Paravicini for Heybrook (who are better known as speaker manufacturers), built by Heybrook here in the UK during the mid and late 80s. There was a matching pre (the C2 - not designed TdP as far as I know) but I have a few pre amps sitting idle already so was only looking for a power amp to get me up and running again. Looking forward to receiving it and giving it a listen.

 

let us know how it goes....

 

Pardon me, but would you be kind enough to explain how the size of the transformer relates to speaker sensitivity? Even a small transformer can still hit the rails with 60V. It's what you do with the voltage afterwards that matters. Some powerful Carver amps have very tiny transformers.

At least a potted toroidal won't give off a physical "buzz" like E-cores, etc.

 

Received the amp a few days ago and have been trying it out yesterday and today, using a passive pre amp to control volume. Initial impressions are very positive: the P2 is extremely quiet in operation, with no hums or buzzes of any kind coming from either the amp itself or through the speakers (with no music playing), and sound-wise it is all positive too. Plenty of grip so bass is clean and extended, much more so than I was expecting via the resistor based stepped attenuator in my passive pre, and the music all hangs toegther nicely.

Having seen the transformer in the flesh, I don't think a lack of size is an issue despite previous concerns raised, as it is actually taller than I expected and reaches up to the full height of the case itself. I will continue to use it with the passive pre for a few more days then give it a try with one or two active pre amps, to see what I think of the pairing, though I could very happily just leave it as is with the passive pre in place.

Test system so far has been Sony CDP-X55ES cd player, DIY passive pre based around a Dale/Vishay resistor based stepped attenuator, Heybrook P2 power amp into KEF 203 floorstanders.